The basic reason for this is because of BTC being the reserve currency of the crypto world. The average person has to get btc to buy alts. Unless there surges a significant alt/fiat market, they are bound to go down in btc value when btc goes up in dollar value. The same goes the other way, if btc goes up alts go up in dollar terms for a while but it is because of the markets still not reacting to that surge and thua preserving the same btc value for a while. After the markets realize btc is up, most alts go down to maintain the previous dollar value.

No I do not think that bitcoin is reserve for trading altcoin, in fact bitcoin is the main currency , that what people are using it for different purposes, even in some places people are using bitcoin for shopping in local shops, in fact we use bitcoin just like our fiat currency for trading, investment as well as for gambling activities.

Come on seriously is this even a question. I suppose you are new to crypto currency in general. Basically people are selling bitcoins and buying altcoins with it. When they buy altcoins price of altcoins increases and btc decreases. Then when btc decreases they buy btc again this leads to increase in price of btc and fall in price of altcoins. Same like buy and sell rate.

simply because alt coins are just depending on the bitcoin, their prices may change when the value of bitcoin changes also, it is the matter of demand and the supply, when the demand will go higher the supply needs to be higher too, therefore the value of bitcoin will go higher and the altcoins will go down because many people invested in bitcoins rather than in alt coins.

Altcoins price were down when bitcoins price raised up, it was due to unbalanced value of currency, because if all Altcoins were balance every time Bitcoin raised up the other altcoins were raised up to, vise versa if they down.

The major reason behind this is that when BTC prices goes up people sell their altcoins to buy BTC. But this is not always true some altcoin remain stable when BTC price goes up. Another reason is that bitcoin is a large currency so its pumping and dumping is not that much easy so people pump and dump altcoin.

Gone are those days now both bitcoin and altcoins are almost moving on the same direction except when the are fundamental issue relating to a particular coin. Many are seeing bitcoin and altcoins as if there are in a competitive market but what I find out is most positive news about altcoins move bitcoin price positively.

Demand of bitcoin not only from cryptotraders but also from outside there. There are many new people may be buy bitcoin the price will be coherent with the law of supply and demand. When bitcoin price rise, and altcoin stand still not amazing because people now only know bitcoin. They not recognize ether, dash and new other coins.

Altcoins are down when bitcoin is up is due to Altcoins dumping, people are converting their altcoins to Bitcoin then exchange to cash. Of course, investors and traders alike are taking advantage of the high price of bitcoin before it dip again. There are some people also hold their altcoins btw.

If we observe the current conditions then there will be a different one, once when Bitcoin rises it automatically altcoin down but now almost nothing like that, even if there is a decrease in altcoin prices when Bitcoin rises it is just a moment and instantly altcoin can go up again, and this is quite surprising.

I don't think this is always true, because most of the time the price of most Altcoins goes up in USD value when BTC rally, it is onlt against BTC that their value dump. This is expected because there are only about 16 million currently in circulation and when price goes up, that means less people are selling their BTC

When Bitcoin surges altcoins usually dumps, so people take advantage to buy the dips. But not all alts dumps when btc rises. I think people sell alts when they see btc pumps so that they can convert bitcoin to fiat or/and also buy dips from alts vice versa.

When Bitcoin surges altcoins usually dumps, so people take advantage to buy the dips. But not all alts dumps when btc rises. I think people sell alts when they see btc pumps so that they can convert bitcoin to fiat or/and also buy dips from alts vice versa.

In my opinion, because mostly Bitcoin is the center of the trade. And currently Bitcoin is on surge in just 2 days it rise up to a 200$. And I agree that it is not always that when Bitcoin goes up everyone coin goes down. The tendency for an Altcoin to be profitable is to watch it's rise in its fluctuation on how many was sent out and how much it rises everyday.